This invention relates to the packaging of bulk quantities of powdered, crystalline or granular organic and inorganic compounds which cake, and in particular a packaging system and method which substantially reduces or eliminates caking of the compounds to maintain the compounds in a substantially free flowing or scoopable state for an extended period of time.
Heretofore, when powdered or crystalline compounds, such as NaCl, KI, KNO3, or other organic or inorganic cakable compounds were packaged in bulk, the compound was normally placed inside a fiberboard drum having a polyethylene liner. The drum was then covered with a fiberboard lid. The compound, when so packaged, invariably cakes, even if measures are taken to prevent or retard caking. In some instances, the compound can cake so severely that it becomes rock solid and must be beaten or crushed before it can be used. This has been especially true of certain salts and other organic and inorganic compounds. Companies spend hundreds of thousands of dollars annually to beat or crush caked compounds so packaged, so that the compounds can be made flowable, or at least scoopable. This severe caking occurs even though desiccant is placed in the drum.
Crushing of caked compounds must, of course, be carried out under controlled circumstances. Procedures must be followed to prevent cross-contamination of compounds and to prevent other impurities from contaminating the compound. This is especially true of drug grade chemicals, the handling of which is governed by the USP. For USP listed chemicals, the chemicals must be processed in accordance with the cGMP (current good manufacturing procedures). Obviously, the need to beat or crush caked compounds adds to the cost of procuring and using the compound. The need to follow the cGMP for crushing a USP listed compound can add even more cost to the process. Beating drums to break up caked compounds is a common practice in the industry. This is an ergonomically and economically poor practice. In can also cause breaking of the drums and allow the products to enter into the environment and/or allow the product to become contaminated.
The caking of chemical compounds has long plagued the industry. Many attempts have been made to alleviate the problem. However, no one has found an acceptable solution. For example in some applications, the compound is heated to 400-500xc2x0 C. to dry the compound thoroughly before packaging. However, when the moisture leaves the compound in the course of this prior method, it may alter the physical shape and size of the compound in a detrimental manner. Another method includes adding anti-caking agents to the compound to be protected. These anti-caking agents coat the particles of the compound to protect them from moisture. However, a specific anti-caking agent may not be acceptable for a wide variety of compounds. The anti-caking agent therefore must be carefully chosen. Further, the use of anti-caking agents is not acceptable in many circumstances. Pharmaceutical compounds, for example, cannot have anti-caking agents mixed with them. The anti-caking agents can detrimentally alter the efficacy of the resulting medicine, or the process for producing the medicine. The use of anti-caking agents is also costly. The anti-caking agent cannot simply be added to the compound to be protected. It must be fully blended into the compound to be protected. Despite the disadvantages of using anti-caking agents, current research in the prevention or reduction of caking appears to be directed to the development of further anti-caking agents.
The current invention provides an inexpensive and practical solution which substantially reduces or prevents the caking of even KI and 2xcexc NaCl and maintains the compounds in a substantially free flowing or scoopable state without adding any anti-caking agents to the compound to be protected.
The following are objects of one or more of the claims of the invention:
One object is to provide a packaging system and method for packaging bulk quantities of powdered, crystalline, or granular organic and inorganic cakable compounds and mixtures thereof which will substantially retard or eliminate the caking of the compounds.
Another object is to provide such a packaging system and method which will maintain the chemical compounds in a substantially free flowing or scoopable state.
Yet another object is to provide such a packaging system and method which eliminates or reduces the need to use anti-caking agents.
A further object is to provide such a packaging system and method which will retard caking in a wide variety of compounds.
An additional object is to provide such a packaging system and method which is not complex and which is inexpensive to implement.
These and other objects will become apparent to those skilled in the art in light of the following disclosure and accompanying drawings.
In accordance with the invention, generally stated, a packaging system and method is provided which will substantially reduce the degree of caking of powdered, crystalline, or granular cakable compounds. The packaging system comprises a moisture impermeable container having a moisture impermeable cover which closes the container to define an enclosure in which the compound is placed, and a desiccant. Means, such as a gasket, can be positioned between the container and cover to create a moisture tight seal therebetween. The compound can be placed directly in the container or it can be placed in a moisture permeable bag. The bag, if used, preferably is sealed after the compound has been placed therein. The container is filled with the compound so that there will be a void space in the enclosure. The desiccant is placed in the void space.
The drum is preferably a fiber board drum lined with a moisture impermeable substance, such as aluminum, plastic, etc. The cover is preferably a plastic cover. Any desiccant may be used. It can be, for example, a silicon based desiccant, such as a desiccant which comprises about 70% silicon oxide, about 20% aluminum oxide, about 5% magnesium oxide, about 3% calcium oxide, and about 2% ferric oxide. One commonly available desiccant has a particle size of which 99% by weight passes 10 mesh and 4% passes 80 mesh and has an apparent bulk density of 60 lbs./ft3 (0.96 gm/cc). The permeable bag may be a crepe paper bag, such as a bag made of 50# kraft paper (Arkel(trademark) paper), or it may be a permeable polypropylene bag, such as a bag made from a woven polypropylene.